DE202016002935U1 - Fluidic system for a medical treatment device, in particular a device for extracorporeal blood treatment, and device for extracorporeal blood treatment with such a fluid system - Google Patents

Abstract

Fluid system for a medical treatment device, in particular a device for extracorporeal blood treatment, wherein the fluid system comprises one or more conduits (2) or channels for guiding a fluid, characterized in that the fluid system comprises a latent heat accumulator (7) connected to a conduit (2 ) or a channel is in thermal contact.

Description

The invention relates to a fluid system for a medical treatment device, in particular a device for extracorporeal blood treatment, which has one or more lines or channels for guiding fluids. In addition, the invention relates to a device for extracorporeal blood treatment with a fluid system having one or more conduits or channels for conducting fluids.

Various procedures for extracorporeal blood treatment are used to remove urinary substances and to remove fluids. In hemodialysis, the patient's blood is purified outside the body in a dialyzer. The dialyzer has a blood chamber and a dialysis fluid chamber separated by a semipermeable membrane. During the treatment, the patient's blood flows via a blood supply line into the blood chamber of the dialyzer and back to the patient via a blood return line. In order to effectively purify the blood of urinary substances, the dialysis fluid chamber is continuously flowed through by fresh dialysis fluid. The dialysis fluid is supplied to the dialysis fluid chamber via a dialysis fluid supply line and discharged from the dialysis fluid chamber via a dialysis fluid discharge line.

The blood and dialysis fluid lines are generally designed for single use tubing sets. In addition to the tubing sets also cassettes are known, which are inserted into the blood treatment devices. The cassettes have lines or channels.

In the case of extracorporeal blood treatment, the blood of the patient may cool down via the semipermeable membrane of the dialyzer due to the thermal interaction with the treatment liquid, in particular dialysis fluid. If the cooling exceeds a tolerable limit, the patient's blood is warmed before returning to the patient. For this purpose, the blood or the dialysis fluid in thermal contact with the blood can be heated.

For the preparation of fresh dialysis fluid, the devices for dialysis treatment generally have a dialysate treatment system, with the fresh dialysis fluid of water and concentrate is produced. For heating the dialysis fluid, the dialysate treatment system has a heating system.

To set a specific reflux temperature for the blood, a control unit for the heating device of the heating system is provided which has a temperature measuring unit which measures the temperature of the blood flowing back to the patient with a temperature sensor. The reflux temperature of the blood can be measured in the blood return line. The target value for the return temperature may correspond to the body temperature. From this target value can be deviated but also. Thus, a slightly reduced reflux temperature can increase the subjective well-being of the patient. Therefore, the known heating systems allow adjustment of a desired temperature.

For the determination of parameters characteristic of a blood treatment, for example the dialysance or clearance, the recirculation or the flow rate of the blood or the dialysis fluid, methods are known which are based on a short-term change in the temperature of the blood flowing in the extracorporeal blood circulation or the dialysis fluid in the dialysis fluid system , The short-term change in temperature is also called the temperature bolus.

The WO1998032477 A1 describes an extracorporeal blood treatment device with a measuring device for determining the recirculation, which generates a temperature bolus upstream of the dialysis fluid chamber of the dialyzer, which leads to a change in the temperature on the blood side. The change in temperature on the blood side in turn leads to a change in the temperature downstream of the dialysis fluid chamber of the dialyzer. To determine the recirculation, the temperature is measured downstream of the dialysis fluid and the recirculation R is determined from the time course of the temperature change.

With a targeted, short-term change in the temperature, the flow rate of a liquid in a pipe can be determined on the basis of a transit time measurement. To determine the flow rate, the time it takes the temperature bolus to advance from a first location of the conduit where the bolus is generated to a second location of the conduit downstream of the first location is measured. The flow rate can then be calculated from the transit time if the distance traveled by the temperature bolus is known.

The generation of a single temperature bolus is not sufficient for a continuous measurement of the flow rates required in an extracorporeal blood treatment, for example for determining the volumes of fluid. Rather, the temperature profile must be continuously modulated. This can be done for example by a pulsed operation of the heater, resulting in a sinusoidal temperature profile. In addition, a synchronization of the measuring device is required at regular intervals, so that the transit time of the correct bolus from the sequence of boli is detected during the transit time measurement. This can be done by encoding the amplitude of the bolus or by omitting one or more boluses in the otherwise regular pattern.

The use of a single liquid heating both for setting a certain reflux temperature and for generating Temperaturboli for the determination of characteristic of the blood treatment parameters has proved in practice to be not advantageous because the control unit of the heating system under the specification of short-term temperature changes is not always the Setting the desired return temperature allowed. Therefore, in the known blood treatment devices for determining the parameters characteristic of the blood treatment, a separate heating device with its own control unit is provided, which can be regulated independently of the heating device for the adjustment of the blood reflux temperature.

In solar thermal systems are used for storing solar energy latent heat storage. Such latent heat storage devices have a storage container for receiving a heat storage medium. The heat storage medium is a phase change material (PCM) that utilizes the enthalpy of reversible thermodynamic state changes to store solar heat. A known phase change material, for example, sodium acetate trihydrate, which has a high enthalpy of fusion and a relatively low price. When loading the latent heat accumulator, the phase change material changes from a solid state of aggregation to a liquid state of aggregation. Sodium acetate trihydrate, for example, is liquefied at a melting temperature of 58 ° C. Upon cooling, the salt hydrate remains liquid as a supercooled melt in a metastable state. Conversely, when crystallization is initiated, the salt hydrate heats up to a temperature of 58 ° C, releasing the latent heat.

The invention has for its object to provide a fluid system for a medical treatment device, in particular a device for extracorporeal blood treatment, which allows both the heating of a liquid and the determination of characteristic of the medical treatment sizes in a simple manner. In particular, the invention has for its object to enable the determination of characteristic of the medical treatment sizes without additional heating and control is required in addition to the heater to set a desired reflux temperature.

The solution of this object is achieved according to the invention with the features of claim 1. The dependent claims relate to advantageous embodiments of the invention.

The fluid system according to the invention is intended for use in a medical treatment device, in particular an extracorporeal blood treatment device. The sterile fluid system has one or more conduits or channels for carrying fluids. The lines or channels may each again have one or more line or channel sections. Also, the fluid system may include other components. However, these additional components need not be part of the fluid system, but may also be part of the device for medical treatment, in particular an extracorporeal blood treatment device. It is not essential to the invention how the liquid is guided in the fluid system. The only decisive factor is that at least one line or channel is available. Furthermore, it is not critical which fluid flows in the conduit or channel, for example blood or dialysis fluid.

The fluid system according to the invention is characterized by a latent heat accumulator, which is in thermal contact with a line or a channel of the fluid system.

The latent heat storage stores thermal energy (heat energy) in the liquid flowing in the duct or duct. Due to the storage of heat energy, the latent heat storage in the line acts as a low-pass filter that does not transmit in the line or channel propagating short-term temperature boli generated upstream of the latent heat storage. In contrast, slower temperature changes can be detected downstream of the latent heat storage. Consequently, the regulation of the heating device for adjusting the reflux temperature of the liquid can be decoupled from the measurement of the variables which are characteristic for the medical treatment. An additional heater with a separate control is not required.

For the invention is irrelevant how the latent heat storage is in thermal contact via the line or channel with the liquid. The latent heat storage may include one or more portions of the duct or duct partially or over the entire circumference. There just needs to be sufficient thermal contact be prepared, so that for loading the memory of the liquid heat to the latent heat storage or for discharging the memory of the latent heat storage heat can be delivered to the liquid.

A preferred embodiment provides that the latent heat storage has a phase change material (PCM). Phase change materials are state of the art. In a particularly preferred embodiment, the phase change material is paraffin or a paraffin mixture. The phase change material may be an organic phase change material having a phase transition between 30 and 40 ° Celsius. However, other phase change materials can also be used.

The fluid system according to the invention is preferably designed as a hose set which can be used in a device for extracorporeal blood treatment and has one or more hose lines which is preferably intended for single use (disposable). However, the fluid system can also be designed as a cassette insertable into a device for extracorporeal blood treatment with one or more lines or channels. Such tubing systems or cassettes as such belong to the prior art.

The extracorporeal blood treatment device according to the invention, for which the fluid system according to the invention is intended, has a heating device which is designed so that a liquid flowing in a line or channel of the fluid system at a first point of a line or channel is at a certain temperature is heatable. The heating device may be a heating device of a conventional dialysate treatment system with which the dialysis fluid is heated to the desired temperature. The heating device can also be a heating device for heating the blood of the patient. Consequently, the conduit or channel with which the latent heat storage device is in thermal contact may be a conduit or channel for dialysis fluid or blood.

In addition, the extracorporeal blood treatment device has a measuring device for measuring a parameter characteristic of the blood treatment, for example the dialysance or clearance, the recirculation or the flow rate of the blood or the dialysis fluid. Such measuring devices belong to the state of the art. For the invention is not essential, as the measuring device is formed in detail. What matters is that the measurement is based on the generation and detection of a temperature bolus that propagates in the conduit or channel.

The measuring device has a control unit that is configured so that the temperature of the liquid flowing at the first position of the pipe or the channel is temporarily changed by the heater, and a temperature measuring unit for measuring the temperature at a downstream of the first position lying second point of the line or channel flowing liquid.

Furthermore, an evaluation unit is provided, which is configured in such a way that, on the basis of a change in the temperature measured by the temperature measuring unit as a result of the short-term temperature change with the heating device, the variable characteristic of the blood treatment can be determined.

The blood treatment device further comprises a control unit for the heating device, wherein the control unit is configured such that the temperature of the liquid at a third point of the conduit or channel located downstream of the second location has a predetermined value or the temperature of one with the liquid in thermally contact other liquid at a third location of another conduit or other channel of the fluid system has a predetermined value.

For example, if the fluid system has multiple conduits or channels, the temperature bolus may propagate through the semipermeable membrane of the dialyzer from one conduit or channel to another conduit or conduit. Thus, the first and second locations and the third location may also be provided on different conduits or channels of the fluid system.

The latent heat storage is located downstream of the second location at which the temperature for the determination of the characteristic size is detected, and upstream of the third location at which the reflux temperature is detected, so that the short-term temperature changes (Temperaturboli) as higher-frequency components not the low-pass filter and can not affect the control of the return temperature.

Consequently, the heating control is decoupled from the calorific determination of the characteristic quantity, for example the caloric flow measurement.

The control unit for the heating device and the control unit for the measuring device may be a common device. This device can also be part of a central control and processing unit of the blood treatment device.

A particularly preferred embodiment provides a measuring device for measuring the flow rate of the liquid flowing in a conduit or a channel. The evaluation unit is preferably configured such that the flow rate of the fluid is calculated from the transit time of a temperature bolus generated at the first location as a result of the short-term change in the temperature of the fluid and the length of the conduit or channel between the first and second locations.

In the most preferred embodiment, the extracorporeal blood treatment apparatus is a dialysis apparatus having a blood supply line leading to a blood chamber of a dialyser divided by a semipermeable membrane into the blood chamber and a dialysis fluid chamber and a blood return line leaving the blood chamber and a dialysis fluid supply line leading to the dialysis fluid chamber having a dialysis fluid outgoing from the dialysis fluid chamber. The first location is in a portion of the dialysis fluid supply line and the second location is in a portion of the dialysis fluid discharge line so that the temperature bolus can be created upstream of the dialysis fluid chamber and detected downstream of the dialysis fluid chamber. The third location is in a section of the blood return line where the reflux temperature can be detected. In this embodiment, the latent heat accumulator is arranged on the blood return line upstream of the third location.

In the following an embodiment of the invention will be explained in more detail with reference to the drawings.

Show it:

1 a simplified schematic representation of the fluid system according to the invention,

2 the inventive medical treatment device with the fluid system according to the invention in a simplified schematic representation and

3 an alternative embodiment of the latent heat storage.

1 shows an embodiment of the fluid system according to the invention as part of the fluid system of a medical treatment device in a highly simplified schematic representation. The fluid system 1 may be a disposable or disposable cassette. The tubing set or cassette can be placed in an in 1 not shown medical treatment device are inserted. In the present embodiment, the hose set or cartridge comprises only one conduit 2 in which a liquid, for example blood of a patient, flows. This line constitutes part of the fluid system of the medical treatment device. The flow direction of the blood is in 1 indicated by an arrow.

To regulate the inflow or return temperature of the blood is a heating system 3 provided that a heating device 4 and a control unit 5 includes. The heater 4 and the control unit 5 are part of the medical treatment device in the present embodiment. In addition, the medical treatment device has a measuring device 6 for determining a size characteristic of the treatment. In the present embodiment, the measuring device measures 6 the flow rate of the fluid, in particular the flow rate of the blood passing through the conduit 2 flows.

The fluid system according to the invention 1 , which may be designed as a tube set intended for single use or as a cassette, comprises a latent heat storage 7 who is in thermal contact with the pipe 2 is so that heat from the liquid to the latent heat storage or from the latent heat storage heat can be delivered to the liquid. The latent heat storage 7 may be part of the tubing set or cassette, ie, also intended for single use, or be a component of the medical treatment device. Preferably, the latent heat storage is discarded after treatment together with the line. Alternatively, the latent heat storage can also be arranged on the machine side and designed such that the disposable fluid line can be inserted into this.

The latent heat storage 7 has a housing body 7A which contains a phase change material PCM which is the lead 2 encloses, so that the thermal contact between the line and phase change material PCM is made. The ratio between liquid and solid phase change material PCM is preferably 1: 1. This has proven to be an optimal operating point. But it can also be set to a different ratio. The phase change material may be an organic phase change material having a phase transition between 30 and 40 ° Celsius. The phase change material may be paraffin or a paraffin mixture. For monitoring the state of the phase change material PCM, sensors, for example optical sensors or pressure sensors, may be provided, which in 1 are not shown.

3 shows an alternative embodiment of the latent heat storage 7 ' in a simplified representation. The latent heat storage 7 ' differs from that with reference to 1 described latent heat storage 7 in that the housing body 7A ' not only with a single phase change material, but with a plurality of different phase change materials is filled, which are arranged in the flow direction one behind the other. This creates a phase transition cascade. Thus, depending on the energy supply, the blood return temperature can optionally be buffered at different values. The housing body 7A ' can through partitions 7a be divided into several compartments, which are filled with different phase change materials.

The advantages of the fluid system according to the invention with the latent heat storage come then to bear if the fluid system in conjunction with the heating system 3 and the measuring device 6 is used, as will be explained in detail below.

The heating system 3 keeps the reflux temperature of the liquid, in particular of the blood, at a desired value. For example, the reflux temperature of the blood is adjusted to the value of the body temperature of the patient. The control unit 5 of the heating system 3 has a temperature sensor 8th on, which measures the temperature of the blood in a section of the lead leading to the patient 2 measures. The control unit 5 compares the actual value of the return temperature with a setpoint and controls the heater 4 such that the actual value corresponds to the desired value. The temperature sensor 8th measures the reflux temperature at a point C downstream of the latent heat storage 7 , Such heating systems are state of the art.

The measuring device 6 for determining the flow rate has a temperature measuring unit 10 on that a temperature sensor 11 which has the temperature of the liquid at a point B of the line 2 upstream of the latent heat storage 7 measures. In addition, the measuring device points 6 a control unit 12 and an evaluation unit 13 on. The control unit 12 is with the heater 4 of the heating system 3 connected to the treatment device, so that the control unit can control the heater.

The measuring device 6 is configured such that the heater 4 the temperature changed briefly, for example, increased, ie at a point A of the line 2 a temperature bolus is generated. To be able to measure the flow rate continuously, a series of temperature boli 14 generated, ie the temperature profile is modulated, which in 1 schematically represented by a sequence of pulses. They are in the lead 2 reproducing Temperaturboli be with the temperature sensor 11 the measuring device 6 recorded at a certain time. In 1 is the result of the Temperaturboli 14 ' at the temperature sensor 11 shown. From the time t ₁ , at which the temperature bolus with the heater 4 was generated, and the time t ₂ , at which the temperature bolus with the temperature sensor 11 is detected, the evaluation unit calculates 13 the transit time .DELTA.t of the temperature bolus over the distance .DELTA.x, between the heater 4 and the temperature sensor 11 lies. From the transit time .DELTA.t and the cross-sectional area of the line 2 determines the evaluation unit 13 then the flow rate. Such measuring devices belong to the state of the art.

The temperature profile of the liquid has a low-frequency and a higher-frequency content. The low-frequency part is due to the regulation of the heating device 4 through the control unit 5 attributed to the setting of the desired reflux temperature, the temperature of the liquid with the heater only relatively slowly increases or decreases. The higher-frequency content is due to the short-term temperature changes to produce the Temperaturboli. The latent heat storage 7 represents a low-pass filter that only lets through the low-frequency part. Therefore, the higher-frequency component can be the temperature sensor 8th the control unit 5 of the heating system 3 do not reach. The temperature profile at the temperature sensor 8th the control unit 5 is in 1 represented by a straight line.

The latent heat storage 7 is designed so that only the low-frequency component is transmitted. The cut-off frequency or bandwidth of the low-pass filter is the melting temperature of the phase change material PCM of the latent heat storage 7 dependent. Therefore, it is possible to adjust the cut-off frequency or bandwidth so that the higher-frequency component is filtered out.

Because the heating system 3 and the measuring device 6 The temperature of the liquid can be used to determine the size characteristic of the treatment from the heater 4 be modulated, with which also the desired reflux temperature is set. Consequently, the structure of the treatment apparatus is simplified.

2 shows an extracorporeal blood treatment device having the fluid system according to the invention. The parts of the blood treatment device of 2 which correspond to those parts of the treatment device of 1 correspond, are provided with the same reference numerals. In 2 only the essential components of the blood treatment device are shown.

The blood treatment device has a dialyzer 15 on, passing through a semipermeable membrane 16 in a blood chamber 17 and a dialysis fluid chamber 18 is disconnected. A blood supply line 19 leads to an inlet of the blood chamber 17 of the dialyzer 15 , and from an outlet of the blood chamber 17 go a blood return line 20 from. For pumping the blood in extracorporeal blood circulation I is in the blood supply line 19 a blood pump 21 connected. The dialysis fluid is in a dialysate treatment system 22 provided a heating system 3 for heating the dialysis fluid prepared from water and concentrate to a predetermined temperature. The outlet of the dialysate treatment system 22 is via a Dialysierflüssigkeitszuführleitung 23 with the inlet of the dialysis fluid chamber 18 of the dialyzer 15 connected. From the outlet of the dialysis fluid chamber 18 performs a Dialysierflüssigkeitsabführleitung 24 to a process 25 , Into the dialysis fluid discharge line 24 is a dialysis fluid pump 26 switched to convey the dialysis fluid.

The measuring device 6 has a temperature measuring unit 10 , a control unit 12 and an evaluation unit 13 on. The temperature sensor 11 the temperature measuring unit 10 measures the temperature of the dialysis fluid in the dialysis fluid discharge line 24 at a point downstream of the dialysis fluid chamber 18 ,

The heating system 3 has a heater 4 and a control unit 5 on that a temperature sensor 8th that has the temperature in the blood return line 20 downstream of the blood chamber 17 measures.

In the blood treatment device is the latent heat storage 7 at a point in the blood return line 20 downstream of the blood chamber 17 and upstream of the temperature sensor 8th arranged.

As with the reference to 1 described embodiment controls the control unit 12 the measuring device 6 the heater 4 of the heating system 3 such that for determining the size characteristic of the blood treatment, temperature boli generated by the temperature sensor are generated 11 the measuring device 6 recorded and with the evaluation unit 13 be evaluated. The latent heat storage 7 at the blood return line 20 prevents the measurement of the return temperature of the blood from being influenced by the determination of the quantity characteristic of the blood treatment.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• WO 1998032477 A1 [0008]

Claims (12)

Fluid system for a medical treatment device, in particular a device for extracorporeal blood treatment, wherein the fluid system comprises one or more lines ( 2 ) or channels for guiding a liquid, characterized in that the fluid system has a latent heat storage ( 7 ), which is connected to a line ( 2 ) or a channel is in thermal contact. Fluid system according to claim 1, characterized in that the latent heat store ( 7 ) has a phase change material (PCM). Fluid system according to claim 1 or 2, characterized in that the phase change material (PCM) is paraffin or a paraffin mixture. Fluid system according to one of claims 1 to 3, characterized in that the fluid system as a hose set which can be inserted into a device for extracorporeal blood treatment with one or more tubing ( 2 ) or an insertable into a device for extracorporeal blood treatment cassette with one or more lines or channels is formed. Device for extracorporeal blood treatment with a fluid system ( 1 ) according to one of claims 1 to 4. An extracorporeal blood treatment device according to claim 5, characterized in that the extracorporeal blood treatment device comprises: a heating device ( 4 ), which is designed such that one in a line ( 2 ) or a channel of the fluid system ( 1 ) flowing liquid at a first point (A) of the conduit or the channel can be heated to a certain temperature, a measuring device ( 6 ) for determining a characteristic size for the blood treatment, the measuring device comprising: a control unit ( 12 ), which is configured in such a way that with the heating device ( 4 ) the temperature at the first point (A) of the line ( 2 ) or the channel flowing liquid is temporarily changed, a temperature measuring unit ( 10 ) for measuring the temperature of the second point (B) of the line located at a downstream of the first point (A) ( 2 ) or the channel flowing liquid, an evaluation unit ( 13 ) configured such that, based on a change in the temperature measurement unit ( 10 ) measured temperature due to the short-term temperature change with the heater ( 4 ) the characteristic characteristic of the blood treatment can be determined, a control unit ( 5 ) for the heater ( 4 ), the control unit ( 5 ) is configured such that the temperature of the liquid at a third point (C) of the line (C) downstream of the second location is ( 2 ) or the channel has a predetermined value, or the temperature of another liquid in thermal contact with the liquid at a third location of another conduit or other channel of the fluid system has a predetermined value, the latent heat storage ( 7 ) is located downstream of the second location (B) and upstream of the third location (A). Device for extracorporeal blood treatment according to claim 6, characterized in that the control unit ( 5 ) a third location (C) arranged temperature sensor ( 8th ) having. Device for extracorporeal blood treatment according to claim 6 or 7, characterized in that the temperature measuring unit ( 10 ) arranged at the second location (B) temperature sensor ( 11 ) having. Device for extracorporeal blood treatment according to one of claims 5 to 8, characterized in that the measuring device ( 6 ) a measuring device for measuring the flow rate of in a line ( 2 ) or a channel flowing liquid, wherein the evaluation unit ( 13 ) is configured such that from the transit time of a temperature bolus generated as a result of a short-term change in the temperature of the fluid ( 14 ) at the first location (A) and the length (Δx) of the conduit ( 2 ) or the channel between the first and second locations (A, B), the flow rate of the liquid is calculable. Device for extracorporeal blood treatment according to one of claims 5 to 9, characterized in that the device for extracorporeal blood treatment is a dialysis device, one to a blood chamber ( 17 ) through a semipermeable membrane ( 16 ) into the blood chamber ( 17 ) and a dialysis fluid chamber ( 18 ) subdivided dialyzer ( 15 ) leading blood supply line ( 19 ) and one from the blood chamber ( 7 ) outgoing blood return line ( 20 ) and one to the dialysis fluid chamber ( 18 ) leading dialysis fluid supply line ( 23 ) and one of the dialysis fluid chamber ( 18 ) outgoing dialysis fluid discharge line ( 24 ) having. Device for extracorporeal blood treatment according to claim 10, characterized in that the first point (A) in a section of the dialysis fluid supply line ( 23 ) and the second location (B) in a section of the dialysis fluid discharge line (FIG. 24 ) and the third position (C) in a section of the blood return line ( 20 ) lies. Device for extracorporeal blood treatment according to claim 10 or 11, characterized in that the latent heat store ( 7 ) at the blood return line ( 20 ) is located upstream of the third location (C).

Images